Investors have rapidly been losing faith in the stock market—one of Wall Street’s most prominent bulls just joined their ranks. In a note Thursday morning, Yardeni Research, a widely respected and closely watched independent research firm, which spent much of the past year cheering on and defending the bull case for U.S. stocks, lowered its 2025 “best case” S&P 500 price target to 6400 from 7000. The S&P 500, which hit a record high of 6144 as recently as Feb. 19, has since tumbled 9.4%, including a decline Thursday, when the index was down 62 points, or about 1%, to 5539.